Little green nudges – Green footsteps lead passersby to a dustbin on the streets of Copenhagen. Researchers found that this decreased the instances of littering by 46%.

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Little green nudges – A recent Dutch study showed that 70% more people chose the stairs instead of the elevator when there were red lines running up them.

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Little green nudges – The "Waterpebble" monitors water going down the plughole when you shower and tells you when to finish showering. It memorizes the length of your first shower and, using it as a benchmark, fractionally reduces your shower time, helping you to save water without thinking about it.

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Little green nudges – Designer Muhyeon Kim has designed a switch that displays how much power it is using. Research has found that people are more conscious of their energy use when they can see it in action.

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Story highlights

"Nudging" is a way of influencing behavior without using force or incentives

Idea is being tested as method to encourage better consideration of environment

Some argue "nudging" is infringement on freedom, others say it does not go far enough

What's the best way of encouraging men to pee more accurately in public urinals? Answer: Give them a target.

That's what a maintenance man working at Amsterdam's Schiphol airport suggested: Etch an image of a house fly on the urinals to give men something to aim at. Overnight, the quantity of misdirected urine fell by about 80%, according to the airport.

The painted fly is an example of a "nudge" -- a subtle way of influencing behavior without offering material incentives or imposing punishments.

"Normally, if a government, employer or even parent wants to promote a certain type of conduct, they introduce rules, offer a financial reward or both," says economist Richard Thaler who, alongside fellow academic Cass Sunstein, popularized the concept of "nudging."

Subliminal sway

Whether we're conscious of them or not, nudges -- of a sort -- are all around us. From the rumble strip along motorways -- gently encouraging motorists to remain in the correct lane -- to rows of brightly colored candy wrappers, less subtly inviting us to pick them up and place them in our shopping cart.

Such subliminal influences are nothing new. But Thaler and Sunstein argue that they have the potential to be harnessed on a much grander scale -- and for the collective good.

"Just imagine if your surroundings were arranged to help you make better decisions to achieve your goals," says Thaler.

The question is, could we be "nudged" into better, more sustainable practices that help the environment?

How bad habits start

Much of our behavior is habitual, says Pelle Hansen, behavioral philosopher at the University of Southern Denmark and chairman of the Danish Nudging Network. "We have long showers, leave appliances turned on and throw away rubbish as part of daily routines that involve little thought."

Some of this automatic behavior is not even in our own long-term interests, let alone the planet's. Hansen points out that dropping litter, for instance, obviously degrades the quality of the shared environment while leaving lights on costs us money.

So why do we do it? The problem is that once a pattern of behavior has formed, it's difficult to break, especially if the negative repercussions are not experienced immediately, says Professor Robert Cialdini, psychologist and author of "Influence: The Psychology of Persuasion."

"Our brains are designed to go into autopilot once we've established a routine that works for us. This is useful because it frees us up to think about things other than day-to-day tasks. But it's also unhelpful if the behavior has negative, albeit not immediately felt, consequences," he adds.

This is where "nudging" could help.

Visual cues

In a study conducted by Hansen's nudging network in Copenhagen, 1,000 caramel sweets were handed out to passing pedestrians. All the nearby streets, including garbage cans, ashtrays, bicycle baskets and so on, were then examined for the distinctive empty wrappers, and duly counted.

The process was repeated, but on this occasion a prominent trail of green footsteps leading up to the nearby bins was stenciled on the ground. This led to a 46% decrease in the total quantity of littered caramel papers (just under 70% of the original total were unaccounted for in both settings), according to the study.

"The green footsteps certainly caught people's attention," says Hansen. "I think they create an atmosphere where the public feel more conscious about litter ... and perhaps there is also a subconscious inclination to follow the feet."

Hansen's remarks echo findings from a recent trial at an office block in Amsterdam which was designed to encourage visitors to take the stairs rather than the power-hungry elevators.

Beginning at the lobby entrance, members of Dutch environmental NGO Hivos lay a series of bright red strips along the floor leading up the stairs. The frequency of people entering the building who opted to take the stairs leapt by 70% during the 24-hour sample period that followed.

"There are a number of forces at play," says Thaler. "Curiosity, novelty and the snowball effect when you see loads of other people suddenly using the staircase."

Policy nudge?

In the UK, nudge theory has been embraced by senior members of the coalition government, who set up the Behavioural Insights Team (BIT) -- popularly known as the "Nudge Unit" -- to research how it could be implemented shortly after coming into office in 2010.

"Nudges appeal to policy makers because they generally don't require huge investments and yet have the potential to make a big impact," says David Halpern, director of BIT.

In its first annual report, released towards the end of last year, the team suggested a range of nudges that could be implemented in the UK. These include the removal of alcohol from conspicuous displays in supermarkets (to discourage excessive drinking) and making residents more aware of how much energy others are consuming.

Knowing how other people behave is often a potent determinant of our own actions. Energy bills that inform users of how they compare with those on the same street or neighborhood are currently being trialled in parts of the UK, says Halpern.

"When you get a bill with a long list of numbers, it's unlikely to mean very much to you. But if you see you're using much more than your next door neighbor, let's say, it suddenly becomes personal."

According to Cialdini, we humans are hardwired to fall in line with the behavior and attitudes of our immediate peers, and so nudges that exploit this trait are likely to succeed.

"MSRI scans in the lab have revealed that when people are led to believe that their opinions differ from the majority of their contemporaries, it activates the pain center of the brain ... so we have a very real incentive to keep in sync with those around us."

But, for some, nudges alone will never be enough. Hannah Kyrke-Smith is a policy adviser for the UK's Green Alliance. She says the problem is less the idea itself and more the policy implications.

"The (UK) government has made quite some noise about the potential of green nudging, but by itself it will never be enough. You can't nudge people towards fully sustainable living, you can't replace regulation ... it needs to form part of a mix of policy tools," she says.